Conductor Specification and Validation for High-Luminosity LHC Quadrupole Magnets

Cooley, L. D.; Ghosh, A.; Dietderich, D.R.; Pong, Ian

doi:10.1109/tasc.2017.2648738

Cited by 36 publications

(41 citation statements)

References 16 publications

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“…Magnets built with conductors of lower Jc would require larger coils, which would lead to a large increase in cost. The Jc of the state-of-the-art Nb3Sn conductors, which are the rod-restack-process (RRP) type, is not as high as we need: even the record Jc reached by the top-performing RRP conductors is 10-15% below the above target [3,4]; moreover, the ~30% spread of Jc among RRP billets which is seen in wires with subelement size (Ds) of 55 μm [3,4] means that in fact a ~45-50% improvement in Jc is required to reach the needs of FCC. After substantial optimization in the past two decades, RRP wires have become excellent technical conductors, and significant achievements have been made in reducing Ds [5], but the Jc performance has been at a plateau since the early 2000s [6].…”

Section: Introductionmentioning

confidence: 85%

Ternary Nb₃Sn superconductors with artificial pinning centers and high upper critical fields

Rochester

Peng

et al. 2019

Supercond. Sci. Technol.

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In this letter we demonstrate the development of ternary Nb3Sn multifilamentary conductors with artificial pinning centers (APC) which achieve high critical fields. These recently-developed conductors were tested in a 31 T magnet, and the results showed that their upper critical field (Bc2) values at 4.2 K are 27-28 T, and irreversible field (Birr) values are above 26 T, values similar to or higher than those of best RRP conductors. The non-Cu Jc has been brought to nearly 1200 A/mm 2 at 16 T and 4.2 K, comparable to RRP, in spite of the fact that the fine-grain Nb3Sn fractions in filaments are still low (20-30%) and the grain sizes are still not fully refined (70-80 nm) due to conductor designs and heat treatments that are not yet optimized. The Nb3Sn layer Jc at 4.2 K, 16 T is 4710 A/mm 2 for the APC wire with 1%Zr, about 2.5 times higher than RRP conductors, in spite of the fact that its grain size is not yet fully refined due to insufficient oxygen and unoptimized heat treatment. An analysis is presented about the non-Cu Jc that can be achieved by further optimizing the APC conductors and their heat treatments.

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Section: Introductionmentioning

confidence: 85%

Ternary Nb₃Sn superconductors with artificial pinning centers and high upper critical fields

Rochester

Peng

et al. 2019

Supercond. Sci. Technol.

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“…Although the highest 15 T Jcs of top-performing RRP conductors can reach 1600-1700 A/mm 2 and are only 15-20% below the FCC specification, due to the inevitable variations among billets in series production [15], at least 40-45% improvement is still required to fulfill the FCC requirement. Luminosity Upgrade [16]. Different symbols represent different designs (see [16] for details).…”

Section: Introductionmentioning

confidence: 99%

“…Luminosity Upgrade [16]. Different symbols represent different designs (see [16] for details). All wires are Ti doped, with dsub of 50-55 μm, and heat treated at 650-665 °C.…”

Section: Introductionmentioning

confidence: 99%

A review and prospects for Nb₃Sn superconductor development

2017

Supercond. Sci. Technol.

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Nb3Sn superconductors have significant applications in constructing high-field (> 10 T) magnets. This article briefly reviews development of Nb3Sn superconductor and proposes prospects for further improvement. It is shown that significant improvement of critical current density (Jc) is needed for future accelerator magnets. After a brief review of the development of Nb3Sn superconductors, the factors controlling Jc are summarized and correlated with their microstructure and chemistry. The non-matrix Jc of Nb3Sn conductors is mainly determined by three factors: the fraction of current-carrying Nb3Sn phase in the non-matrix area, the upper critical field Bc2, and the flux-line pinning capacity. Then prospects to improve the three factors are discussed respectively. An analytic model was developed to show how the ratios of precursors determine the phase fractions after heat treatment, based on which it is predicted that the limit of current-carrying Nb3Sn fraction in subelements is ~65%. Then, since Bc2 is largely determined by the Nb3Sn stoichiometry, a thermodynamic/kinetic theory was presented to show what essentially determines the Sn content of Nb3Sn conductors. This theory explains the influences of Sn sources and Ti addition on stoichiometry and growth rate of Nb3Sn layers. Next, to improve flux pinning, previous efforts in this community to introduce additional pinning centers (APC) to Nb3Sn wires are reviewed, and an internal oxidation technique is described.Finally, prospects for further improvement of non-matrix Jc of Nb3Sn conductors are discussed, 2 and it is seen that the only opportunity for further significantly improving Jc lies in improving the flux pinning.

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“…This system, often referred to as inner triplet, will be composed of four separate electrical circuits, each including six 150 mm aperture, two-layer, Nb 3 Sn quadrupole magnets (MQXF), four of which with a magnetic length of 4.2 m (MQXFA) and two of 7.15 m (MQXFB) [4]- [7]. The main parameters of these magnets are summarized in Table I [4], [7], [8], and its magnetic field map in one half pole is shown in Fig. 1a.…”

Section: Introductionmentioning

confidence: 99%

“…An effective and fast heating mechanism is required to transfer most of the coil to the normal state in a few tens of millisecond, thus quickly discharging the magnet [4], [7], [8].…”

Section: Introductionmentioning

confidence: 99%

Quench Protection Performance Measurements in the First MQXF Magnet Models

Ravaioli

Ambrosio

Bajas

et al. 2018

IEEE Trans. Appl. Supercond.

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Abstract-CERN and US LARP (LHC Accelerator Research Program) are jointly developing Nb3Sn quadrupole magnets to be installed in the LHC for its upgrade to higher luminosity. These magnets' quench protection system will include a combination of quench heaters attached to the coil surfaces and CLIQ units electrically connected to the magnets. Different protection elements have been characterized separately and simultaneously by implementing them on two 1.2 meter long model quadrupole magnets, tested at FNAL and CERN, and one 4.0 meter long mirror magnet tested at BNL. After analyzing the test data, their performances have been positively evaluated. Furthermore, the electro-thermal transients occurring after a quench have been simulated with the LEDET software and the results compared to experimental results. The preferred quench protection system configuration relies both on heaters and CLIQ. This solution is based on electrically robust components, achieves an effective reduction of the coils hot-spot temperature after a quench, and offers increased redundancy against component failures.

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Conductor Specification and Validation for High-Luminosity LHC Quadrupole Magnets

Cited by 36 publications

References 16 publications

Ternary Nb₃Sn superconductors with artificial pinning centers and high upper critical fields

Ternary Nb₃Sn superconductors with artificial pinning centers and high upper critical fields

A review and prospects for Nb₃Sn superconductor development

Quench Protection Performance Measurements in the First MQXF Magnet Models

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Conductor Specification and Validation for High-Luminosity LHC Quadrupole Magnets

Cited by 36 publications

References 16 publications

Ternary Nb3Sn superconductors with artificial pinning centers and high upper critical fields

Ternary Nb3Sn superconductors with artificial pinning centers and high upper critical fields

A review and prospects for Nb3Sn superconductor development

Quench Protection Performance Measurements in the First MQXF Magnet Models

Contact Info

Product

Resources

About

Ternary Nb₃Sn superconductors with artificial pinning centers and high upper critical fields

Ternary Nb₃Sn superconductors with artificial pinning centers and high upper critical fields

A review and prospects for Nb₃Sn superconductor development